Independent Okhotsk plate motion is tested using three main block configurations. In our 3-plate system we assume that the Okhotsk region is part of the North American plate and Amuria belongs to Eurasia. Our 4-plate model allows the Okhotsk block to rotate independently while the 5-plate model also includes an independently rotating Amurian block. Our inversions favors a scenario with independent Okhotsk plate motion but does not formally require it. The F-test statistic indicates that the improved fit is significant at 92% confidence. Independent Amurian plate motion is significant only at 69% confidence. The best fitting poles of rotation for our 5-plate model are shown in Figure 13.37.

Figure 13.37: Poles of rotation for the Amurian, Okhotsk, and Eurasian plates. Error ellipses represent 95% confidence bounds. Triangles represent the locations of the GPS sites used in this study.
\epsfig{file=apel05_1_2.eps, width=8cm} \end{center} \end{figure}

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